Scanning antenna system for horizontally and vertically polarized waves



July 4, 1961 c. A. VAN STAADEN 2,991,473

SCANNING ANTENNA SYSTEM FOR HORIZONTALLY 7 AND VERTICALLY POLARIZED WAVES Filed Oct, 2, 1956 3 Sheets-Sheet 1 IA/vA-A/ro i CORNEL/S l ucusrww m/v She/905M y 1961 c. A. VAN STAADEN 2,991,473

SCANNING ANTENNA SYSTEM FOR HORIZONTALLY AND VERTICALLY POLARIZED WAVES Filed Oct. 2, 1956 3 Sheets-Sheet 2 Fig. 2

[A/Vf/VfOR CORA/'L/S 190a usmv 4/3 wm/ JmwzM-A/ How firrORA/i r 2,991,473 ALLY c. A. VAN 'STAADEN SCANNING ANTENNA SYSTEM FOR HORIZONT AND VERTICALLY POLARIZED WAVES is Sheets-Sheet 3 July 4, 1961 Flled Oct 2 1956 I /v VEA/ TOR Co RNEL /s #0005 I'M/0s l/mv 32-0505 Patented July 4., 1961 SCANNING ANTENNA SYSTEM FOR HORIZON- TALIJY AND VERTICAL'LY POLARIZED WAVES Cornelrs Augustinus van Staaden, Hengelo, Netherlands, assrgnor to N.V. Hollandse Signaalapparaten, Hengelo, Netherlands, a Dutch company Filed Oct. 2, 1956, Ser. No. 613,466

Claims priority, application'Great Britain Oct. 3, 1955 1 11 Claims. (Cl. 343-838) The invention relates to a directive aerial possessing a beam concentrating device, such as a reflector or a lens, and a radiator. For many purposes it is desirable that the aerial should be capable of producing beams of various shapes, two different shapes, for instance. If a rotation symmetrical beam is required, the beam concentrating device must be irradiated by a source of radiatron situated in the focal point of the beam concentratmg device and producing a rotational symmetrical conical beam of radiation, every part of which beam hits the beam concentrating device. This source of radiation may be a circular wave guide nozzle or a doublet with suitable reflector doublets. If a beaver tail beam is required the irradiated part of the beam concentrating device must be large in the direction of the smallest dimension of the beam and small in the direction of the largest dimension of the beam. In order to obtain such an irradiation of the beam concentrating device a suitably constructed source of radiation must be applied; this may be a flat horn radiator, the broadest side of which is parallel to the broadest side of the beam, or a suitable system of doublets and reflector doublets.

In order to obtain a fairly narrow beam the radiator must be situated in, or in the immediate vicinity of, the focal point of the beam concentrating device, so that the two radiators of an aerial capable of producing two different beams would have to be situated in the same position. This being impossible, it is necessary to replace one radiator by another in order to obtain another beamshape. The exchanging of the radiators may, under certain circumstances, be undesirable.

Similar complications may occur if it is necessary to cause either one of two types of scanning motions to be performed by the beam. In this case, as a rule, the beam shape must also be altered, necessitating the replacement of the radiator by another one. But even in the case of both scanning motions being performed by the same type of beam, yet all the same different scanning mechanisms must, as a rule, be applied in order to cause different scanning motions. Consequently, the change of the scanning motion will also necessitate the replacement of the radiator, or the radiator mechanism by another one.

It is the object of the present invention to obviate the necessity of exchanging the radiator and scanning mechanism.

According to the invention the directive aerial is built in such a way that a polarised auxiliary reflector which shows a maximum of transparency for electro magnetic waves of a certain direction of polarisation and a maximum of reflection for electro magnetic waves, the po1arisation of which is perpendicular to the said direction, is situated between the radiator and the beam concentrating'device, the radiation emitted by the said radiator having such a polarisation direction that it passes through the auxiliary reflector without substantial energy losses, whilst the aerial possesses a second radiator emitting a radiation in the direction of the auxiliary reflector the polarisation direction of which radiation is such that the auxiliary reflector is capable of reflecting it, the radiation being reflected in the direction of the beam concentrating device as. the result of the relative position of the latter, device, the second radiator and the auxiliary reflector.

The auxiliary reflector causes a virtual image of the second radiator to be produced at the point where the first radiator is situated, and the beam concentrating device produces a beam which corresponds to the beam which it would produce if a radiator corresponding to the second radiator were situated on the spot where the first radiator is mounted, it thus being unnecessary to remove the first radiator and replace it by the second one. In order to produce beams of different shapes the two radiators may be shaped differently. Moreover, one of the radiators or even both radiators may be capable of performing scanning motions.

In an effective form of an aerial according to the invention one of the radiators is capable of performing a linear scanning motion causing the axis of the beam of the aerial to swing in a certain plane between two extreme positions, whereas the other radiator is capable of performing a circular motion causing the beam to perform a conical scanning motion. A target which is to be followed by the aerial, can first be searched for by means of a linearly scanning beaver tail beam produced by the first radiator whilst the aerial is performing a searching motion by rotating around an axis which is perpendicular to the axis around which the linear scanning is being efiected. After the target has been found and the aerial has been aimed at this target, the other radiator can be made operative, causing a conically scanning beam to be produced by the a erial, so that the aerial can cooperate with a device for automatically following the target. Other combinations of beam shapes or scanning motions may be realised according to the invention.

In a special form of an aerial according to the invention the auxiliary reflector is capable of a reciprocating or oscillating motion for the purpose of causing a scanning motion of a beam produced by a radiator which has a fixed position relative to the beam concentrating device and the radiation of which is reflected by the auxilary reflector. Such a motion of the auxiliary reflector can also be applied to cause an auxiliary scanning motion of a beam, the main scanning motion of which is caused by the movement of the radiator.

The invention will be better understood from the following description, taken in conjunction with the accompanying drawings in which FIG. 1 shows a first form of an aerial according to the invention. FIGURES 2, 3, 4, 5, and 6 show other forms of an aerial according to the invention capable of producing beams of radiation which perform scanning motions. FIG. 7 shows a beam concentrating device to be applied in an aerial according to the invention.

Referring to FIG. 1, part 101 is a cross section of a parabolic reflector. A waveguide 104, terminated by a flat horn radiator 105, passes through an opening in the centre of the parabolic reflector. The horn radiator radiates in the direction of a flat auxiliry reflector 106, which reflects the radiation in the direction of the parabolic reflector 101, as a result of which this radiation appears to be produced by the virtual image of the radiator 105 caused by the reflector 106.

The dimensions of the flat horn radiator are such that the parabolic reflector is completely irradiated in the direction perpendicular to the broadest side of the horn radiator and is only partly irradiated in the direction of the broadest side of the horn radiator, so that a better beam concentration is. effected in the direction perpendicular to the horn radiator than in the direction of the broadest side of the horn radiator resulting in a beaver tail beam being produced.

The auxiliary reflector consists of parallel conductors. The direction of the magnetic vector of the radiation produced by the horn radiator 105 is preferably perpendicular to or is at least substantially different from the direction of the conductors which form part of the auxiliary reflector, so that this auxiliary reflector is capable of reflecting the energy radiated by the horn radiator. At the other side of the auxiliary reflector 106 a second radiator is mounted which in this case is the circular wave guide nozzle 107. The direction of the electrical vector of the radiation produced by this nozzle is perpendicular to or is at least substantially different from the direction of the conductors which form the auxiliary reflector, so that the radiation produced by this. second radiator passes practically without energy losses through the auxiliary reflector, and irradiates the parabolic reflector 101, the latter concentrating this radiation into a pencil beam.

The dimensions of the circular wave guide nozzle are such that the beam of radiation produced by it completely irradiates the parabolic reflector which will be rotation-symmetrical unless an off-set feeding of the reflector is applied.

Although the image of the horn radiator 105, from which the parabolic reflector appears to be radiated when the said horn radiator is active, is situated in the opening of the circular wave guide nozzle, it is nevertheless unnecessary to replace one nozzle or radiator by the other in order to cause a beam of another shape to be radiated.

In the form described the aperture angle of the pencil beam is the same as the beam width of the beaver tail beam in the direction perpendicular to the flat horn radiator. If a larger beam width of the pencil beam is desirable, the circular wave guide nozzle must be made larger, causing it to irradiate only part of the parabolic reflector. It would then be possible to reduce the dimension of the parabolic reflector in the direction of the broadest side of the flat horn radiator, as the extreme parts of the reflector surface in this direction are neither irradiated by the horn radiator nor by the circular wave guide nozzle. As only a part of the remaining reflector surface need be capable of reflecting radiation from both radiators, the extreme parts of the reflector surface in the direction perpendicular to the broadest side of the horn radiator can be built in such a way that they are only capable of reflecting radiation the polarisation direction of which corresponds to the radiation from the flat horn radiator, this simplification reducing the cost of the reflector. The aerial radiates either a beaver tail beam or a pencil beam, depending on which of the radiators is active. The beaver tail beam is suitable for searching; for this purpose the reflector must be caused to swing around an axis which is parallel to the broad side of the beam whilst in addition it performs a searching movement around an axis which is perdenicular to the said first axis. After the target has been found and the aerial aimed at this target, the aerial can be switched over to the circular radiator, after which it produces a pencil beam which permits distance measurements at a greater distance.

Automatic following of the target with the aerial described becomes possible when an eccentn'cally rotatable wave-guide nozzle is applied instead of a fixed circular wave-guide nozzle 107. The beam produced by the aerial when this eccentrically rotatable wave-guide nozzle is active performs a conical scanning movement, so that the position of the target relative to the aerial can be established by comparing the echo pulses received in various positions of the beam during its conical scanning motion.

FIG. 2 schematically shows an aerial possessing two radiators ,both capable of performing scanning motions. The first radiator is a flat horn radiator 205 terminating a movable wave-guide 204 fed by the fixed wave-guide 202 to which it is coupled by means of a hinged waveguide joint 203, situated behind the parabolic reflector 2.01, so that the wave-guide and the horn radiator are a ah stsw gs a r u n x Whi his e end ular to the axis of symmetry of the parabolic reflector. The horn radiator radiates in the direction of a flat. auxiliary reflector 206, of the type described with reference ot FIG. 1, which reflects the radiation of the horn radiator in the direction of the parabolic reflector 201, as a result of which this radiation appears to be produced by the virtual image of the radiator'205 caused by the reflector 206. The wave-guide 204 is caused to swing upwards and downwards by a suitable driving mechanism as 'a result of which the virtual image of the radiator in the auxiliary reflector 206 also moves up- Wards and downwards. This causes the beam produced by the parabolic reflector 201 to swing with respect to this reflector around an axis which is parallel to the axis around which the wave guide is caused to swing. At the other side of the auxiliary reflector 206 a second radiator, which is an eccentrically rotatable wave-guide nozzle 207, is mounted. The polarisation direction of the radiation originating from this radiator is such that this radiation passes through the auxiliary reflector without substantial energy losses. Whilst the eccentricallyrotatable wave-guide nozzle'is radiating the aerialproduces a pencil beam which performs a conical scanning motion. Searching is effected with this aerial by means of the swinging beaver tail beam produced by the flat horn radiator 205 whilst'the aerial reflector is effecting a searching motion around an axis which is perpendicular to the axis around which the wave-guide 204'is' caused to swing. After the target has been found and the aerial has been aimed at this target, the radar set, identified in FIG. 1 and indicated in other figures by the arrowheads, is switched over to the eccentrically rotatable wave-guide nozzl 207, after which the aerial can be aimed at a target with great precision, either by means of an automatic following system or by means of a scope showing the position of the target with respect to the aerial.

It may be regarded as less desirable that the waveguide and its horn radiator 205 are situated in the field of radiation of the eccentrically rotatable wave-guide nozzle 207, as well as in its own reflected field of radiation. These parts cause energy losses, side lobes of the beaver tail beam as well as of the conically scanning beam, and a shadow in both beams. In those cases it is considered necessary to avoid the placing of metal parts in the field of radiation of the eccentrically rotatable wave-guide nozzle, and the construction shown in FIG. 3 is then to be preferred. In the aerial shown in this figure the auxiliary reflector is inclined with respect to the symmetry axis of the parabolic reflector in consequence of which the wave-guide 304 and the horn radiator 305 can be situated beyond the beam of radiation by means of which the eccentrically rotatable waveguide nozzle 307 irradiates the parabolic reflector 301. The wave guide 304 is coupled to a fixed wave-guide 302 by means of the hinged wave-guide joint 303, so that this Wave-guide and its radiator can be made to swing around an axis which is perpendicular to the axi's'of symmetry of the parabolic reflector, causing the beam of radiation produced by the aerial to perform a linear scanning motion.

When in an aerial according to the invention the radiator, the radiation of whichis reflected by the auxiliary reflector, performs a scanning motion, the auxiliary reflector itself remaining meanwhile in a fixed position, which is the case in the 'aerials shown in the FIGURES 2 and 3, th impedance by which the wave-guide is tenninated varies, and consequently the standing wave ratio is not constant. A suitable adaptation of the wave-guide system to its termination, causing it to be a resistance as seen from the magnetron, is in this case seriously im peded. Should the divergences from a correct adaptation of the wave-guide system become too large, then itwill be necessary to apply a constructionof the aerial accordu to th m t ouwhere h auxilia y. reflectorissupported by, and moves together with, the scanning waveguide system the radiation of which is reflected by the auxiliary reflector. In the aerial shown in FIG. 2 the auxiliary reflector 206 must then be supported by the wave-guide 204, and partake in the motion of this waveguide.

The mounting of the auxiliary reflector on the swinging wave-guide has yet another advantage. As the auxiliary reflector is not transparent for the radiation produced by the horn radiator 205, it also forms an obstacle for the beam originating in this radiator after being concentrated by the parabolic reflector 201. It is, therefore, desirable that the auxiliary reflector should be as small as possible. When, however, this auxiliary reflector is fixedly mounted it must be capable of reflecting the radiation emerging from the horn radiator, even in the extreme positions of this horn radiator, thus causing all energy emerging from the said horn radiator within the limits of its beam to be reflected in the direction of this parabolic reflector. Consequently, the auxiliary reflector must be elongated in the scanning direction. When the auxiliary reflector is supported by the moving waveguide, and, consequently, the radiator does not move with respect to this auxiliary reflector, it is obvious that this auxiliary reflector can be made smaller.

In the aerial shown in FIGURE 3 it is not possible to support the auxiliary reflector on the swinging waveguide, as in that case the. image .of the radiator 305 would not move perpendicularly or nearly perpendicularly to the direction of the beam, but would move in the direction towards and away from this parabolic reflector. This would only cause a variation of the section of the beam and not a scanning motion of it.

When it is not permissible for the horn radiator and the wave-guide supporting it to be situated in the field of radiation of the eccentrically rotating wave-guide nozzle and when it is not feasible to apply the construction according to FIG. 3, for instance because it is desirable to support the auxiliary reflector on the swinging wave-guide feeding the horn radiator, the construction according to FIGURE 4 or FIGURE 5 must be used, which figures do not need any further elucidation.

In the construction shown in FIG. 5 the swinging wave-guide is shorter than in the construction according to FIG. 4, but part of the wave-guide is still situated in the field of radiation of the horn radiator as well as of the rotatable nozzle the field strength near the wave guide being, however, considerably lower than in the immediate vicinity of the rotatable wave guide nozzle.

FIG. 6 shows another form of anaerial according to the invention in which an eccentrically rotatable wave guide nozzle 607 is situated between the auxiliary reflector and the parabolic reflector, and is fed by a circular wave-guide 608 passing through an opening in the centre of the parabolic reflector and rotated by a motor which is situated behind this parabolic reflector. Part 606 is the auxiliary reflector supported by the supporting device of the flat horn radiator 605,which, as seen from the parabolic reflector, is situated behind this auxiliary reflector. The horn radiator 605 is fed by a wave guide 604, which is coupled to a fixed feeding wave-guide 602 by means of a hinged wave-guide, joint 603. An arm 609, the shape of which corresponds to the shape of the feeding wave-guide 604, completes the support of the horn radiator and the auxiliary reflector, and causes the obstacles to radiation formed by the radiator, the waveguide and their support to be-symmetrical with respect to the aerial reflector. Conical scanning occurs when the aerial is fed by the rotating nozzle 607, whilst linear scanning occurs when the aerial is fed by the flat horn radiator 605 swinging around the joint 603, a corresponding hinge, supporting the arm 609.

The auxiilary reflector can be applied in order to cause the scanning motion of the beam produced by the radiator the radiation of which is reflectedby the auxiliary reflector, this radiator itself remaining in a fixed'posi-t tion withrespect to the parabolic aerial reflector. Linear? scanning motion, during which the axis of swings in a plane between two extreme positionsgcan be. obtained by causing the auxiliary reflector to oscillate; around an axis which is perpendicular to the plane in which the linear scanning is to take place. In the aerial according to FIG. 1 for instance, a linear scanning motion of the beam produced by the horn radiator could be obtained by causing the auxiliary reflector to oscillate around an axis whichis parallel to the opening of the flathorn radiator. Unless the polarisation direction of the radiator which produces the conically scanning beam itself rotates, spinning of the auxiliary reflector about an axis 'which is nearly perpendicular to the surface of the auxiliary reflector for the purpose of causing a conicalscanning motion is not feasible, as it is not permissible for the conductors of the auxiliary reflector to change their position substantially with respect to the polarisation directions of the radiation from the two radiators during the scanning motion of the auxiliary reflector. Should it be necessary to obtain a conical scanning motion as a result of movement of the auxiliary reflector, this reflector must be caused to swing around two nonparallel axes. I

If the polarisation direction of the radiation partakes in the rotation, for instance owing to the fact that the radiator is a doublet partaking in the rotation, the coni cal scanning motion can be obtained by causing the auxiliary reflector to spin around an axis which is not perpendicular to its surface. It is then, however, necessary to lock this auxiliary reflector in such a position that it will not impede the passage of the radiation ofthe other radiator when the beam produced by the radiator situated behind the auxiliary reflector is to be emitted.

An auxiliary scanning motion according to either the British application for patent 5,938/54 or 5,937/54 can also be obtained by means of the auxiliary reflector. 'If the main scanning motion is caused by an oscillating motion of the radiator, the auxiliary scanning motion can be obtained by causing the auxiliary reflector to oscillate around an axis which is not parallel to the axis around which the main scanning motion occurs. If the radiator producing the beam is stationary the main scanning motion can-be obtained by causing the auxiliary reflector to swing around a first axis, whilst the auxiliary scanning motion can becaused by an oscillation of the auxiliary reflector of a much smaller amplitude around a second axis. 'It' needs no further elucidation that scanning motions according to the British applications for patent mentioned above can also be obtained by causing a radia-j tor, the radiation 'of which is reflected by an auxiliary reflector according to the invention to perform the main scanning motion as well as the auxiliary scanning mo-, tion, the auxiliary reflector remaining stationary.

In order tojobtain a beam of a required shape, the beam concentrating device'must have a surface suitable for producing a beam of this shape, which surfaceis to be completely irradiated'by the radiator mounted for the purpose of producing the said beam. If beams of various shapes must be produced asis the case in the aerialaccording to the invention, the shape of the total surface of the beam concentrating device, such as a reflector, must at any rate be such that it comprises the shape neces sary for any beam shape to'be produced, a suitable part of this surface being irradiated for the purpose of producing 'a beam of a certain required shape. The restriction of the irradiation of the surface of the beam concentrating device is effected .by a suitable method of construc tion of the radiator. This radiator may, however, be assisted in its task of restricting the active part of the beam concentrating device by constructing the latter device in such a way that only a certain part of it is capable of concentrating radiation the polarisation direction of which corresponds to the polarisation direction of the radiation emitted by the first radiator, whilst only acertain other part of it, is capable of concentrating radiation the polarisation direction of which corresponds to the radiation originating from the other radiator; as these two partsoverlap, the overlappingpart or the beam concentrating device is capable of concentrating radiation originating from both radiators. For this purpose a beam concentrating device of the reflector type can be constructed by applying two sets of conductors, one set of conductors being perpendicular or nearly perpendicular to the electrical vector of the radiation emanating from one of the radiators, and the other set of conductors being perpendicular or nearly perpendicular to the electrical vectorof the radiation emanating from the other radiator, the twosets of conductors being mutually perpendicular or at least practically mutually perpendicular. Every one of these two sets of conductors will reflect the radiation. of which the magnetical vector is perpendicular or nearly perpendicular to the direction'of, the conductors, the overlapping part in which conductors of both types are present reflecting radiation of the one as well as of the other polarisation direction. In many cases it will be sufiicient if the complete aerial reflector is capable of reflecting the radiation emanating from one radiator, whilst part of the reflector is capable of reflecting radiation emanating from the one as well as from the other radiator. In the case, for instance, of an aerial in which no ofiset feeding is applied and which is capable of producinga linearly scanning beaver tail beam as well as a conicaily scanning pencil beam, a rotational symmetrical part'of the aerial reflector must be capable of reflecting radiation of both polarisation directions whilst parts of' the reflector surface forming extensions at both sides inthe v direction of the linear scanning, are only capable of reflecting radiation the polarisation direction of which corresponds to the polarisation direction of the flat horn radiator producing the beaver tail beam.

Although in this specification the invention has up till this point been especially described for an aerial capable of producing a linearly scanning beaver tail beam and aconically scanning pencil beam, it is also suitable for many other purposes. In a radio beacon for instance the sameaerial reflector can be used to produce a fan shaped beam, indicating the direction of a run-way, as well as a second beam giving glide path indication. The two bearngcan be caused to be simultaneously. active for instance by pulsing the, two radiators alternatively. In the aerials according to the invention described by way of example in this specification, a parabolic reflectorhas beenappliedas the beam concentrating device. It is obv ousnthat instead of a reflectona lens can be applied equally well, and that measures similar to those described above can be taken to restrict the concentration of radi-. ation ,of a certain" polarisation direction to a part of the lens surface. I

:7 The radiator which is situated between theauxiliary reflector and the beam concentrating device will, as a rule, intercept a part of the radiation emitted-by the radiator situated at the other side of the auxiliary reflector. This interceptionshould be reduced as far as possible. If the first mentioned radiator is capable of performing a scanning motion, the scanning'mechanism can cause it to be in such a position when the second radiator operates that, in any case onlya small .part of the first radiator is in the beam of the second one. According to the invention the aerial can be provided 'with locking means capable of lockingthe first" radiator in a" position in which it is at a maximum distance from the centre of the beam of the second radiator.

What I claim is:

1. A directive aerial array for an' electromagnetic wave energy apparatus, said array comprising, in combination, beam concentrating means, first and second beam radiating means ielectrically'connectable to said'apparatus, at least one of said radiating means being movably mounted,

the movable oneof the radiating means causing a scanning motionof the respective beam, polarized auxiliary beam reflecting means having a maximum transparency for electromagnetic waves in a predetermined direction of polarizationand having maximum reflection for electromagnetic waves in the direction of polarization perpendicular of said predetermined direction, said auxiliary beam reflecting means being situated between said first and second ,radiating means, and said first radiating means being situated between said beam concentrating means and said auxiliary .beam reflecting means, the radiation emitted by said first radiating means having a polarization in a direction in which said radiation passes through said auxiliary beam reflecting means, and the radiation of the second radiating means being directed toward the auxiliary beam reflecting means, said radiation of the second radiating means being polarized in a direction in which said radiation is reflected toward said beam concentrating means, said two radiating means having radiation diagrams diflerent from each other to cause two beams of different. cross-sectional configuration to be radiated by the aerial arraywhereby said first and second radiating means are energized at preselected periods for transmitting electromagnetic energy from said apparatus.

2. An aerial array according to claim 1, wherein said first radiating means are. mounted for performing a circular motion about the center axis of said beam concentrating means, said motion causing a conical scanning motion of therespective one beam.

3. An aerial array .according to claim 1, wherein said second radiating means are mounted for performing a substantially linearreciprocatory motion of limited amplitude defining a spatial angle with the center axis of said beam concentratingrmeans, said motion causing a scanning motion of the respectivebeamin a plane.

4; .,An '.aerial. arrayaccording to claim 1, wherein said auxiliarymeflectingmeans and second radiating means are mounted on a common support.

5., aeri l. array according to claim 4, wherein said common support is mounted for performing a substantially linear reciprocatory motion of limited amplitude at an angle with the center axis of said beam concentrating, means, said motion causing a corresponding scanning motion of, the respective beam in a plane.

.6. An aerialyarray-aceording to claim 1, wherein said auxiliary reflecting means is movable relative to said second radiating means wherebya movement of said reflecting means causes an auxiliary scanning motion of the respectivetbe'am r 7. An aerial array according to claim 1, wherein said second radiating means are mounted for performing a substantially linear reciprocatory motion of limited amplitudeat-anangle with the center axis of said beam concentratingv means, said linear motion causing corresponding planar motion of the respective beam, and said second radiating means being further mounted to perform a second niotionin adirection different from but of smaller amplitude than said firstrnotion, said second motion causing an auxiliary scanning motion of the respective beam.

,8. An -aerial array according to claim 1, wherein said beam concentrating means comprises a portion concentrating a radiation beam having a polarization corresponding to the nadiation of said first radiating means and a radiationbeam having a polarization corresponding to theradiation of the second radiation means, the remaining portion of said beam concentrating means concentrating only a beam having a direction of polarization corresponding to the radiation emitted by one of said radiating means.

9. ,An. aerial array beam concentratingmcans comprises a first portion concentrating a radiation beam having a polarization corresponding to the radiation of the first radiating means, a second portion concentrating a radiation beam having a polarization corresponding to the radiation of the second radiat ng means, and athird' portion concentrating beams according to claim 1, wherein said having a direction of polarization corresponding to both directions of polarization.

10. An aerial array according to claim 1, wherein said first radiating means are mounted for performing a circular motion about the center axis of said Beam concentrating means, said motion causing a conical scanning motion of the respective beam, and comprising locking means for arresting said movable first radiating means in a position in which a fractional part only of said first radiating means is impinged by the beam of said second radiating means.

11. An aerial array according to claim 1, wherein said second radiating means are mounted to perform a circul-ar motion about an axis substantially perpendicular of the center axis of said auxiliary reflecting means, said 15 1,098,286

10 circular motion causing a conical scanning motion having a direction of polarization rotating in correspondence with the scanning motion, and comprising locking means for retaining said first radiating means in a position in which the radiation beam thereof traverses said auxiliary reflecting means at minimum losses.

References Cited in the file of this patent UNITED STATES PATENTS Blitz Sept. 19, 1950 2,680,810 Korman- June 8, 1954 FOREIGN PATENTS 743,533 Great Britain Jan. 18, 1956 France July 21, 1951 

